Valentine, a detective constable with Tauranga Police, enjoyed his role working with some of the best young talent in New Zealand and Australia.
"My job was to help bring these players through from school football to the development leagues they play in, then on to the Storm.
"There's a lot of good kids who go through that system up there. It's a pretty professional network they have got going.
"It's quite interesting to see these raw-boned kids come through, including guys like Greg Inglis and Adam Blair, who didn't know how to do a thing. I taught them how to exercise properly as far as strength and conditioning work, and also about nutrition and periodisation, which is essentially an annual plan."
Valentine held Inglis up as a model for what can be done with an athlete.
"He was a bit gangly to be honest. If you saw photos of him going through the schoolboy process he was always very tall but quite gangly. If you look at him now he is really, really well built.
"People have done a great job with him."
He believes a wider adherence to training principles among amateurs in the last five years to be closing the gap between the haves and the have-nots.
"It used to be special for a strength and conditioning coach to work with a team, but some of these guys are incredibly fit and have knowledge about their own bodies and strength and conditioning.
"Their training ethos is on a par with the professional guys and they work just as hard."
He admits these gains have led to a more defensive game in which teams work harder for their points.
"It is a lot easier to work on stoic defence than it is to work on the subtleties of attack. It's easier to be a solid defensive player because all it really takes is commitment, whereas being an attacking player is a skill thing."